Phthalocyanine compounds are useful as coatings, printing inks, catalysts or electronic materials. In recent years, they have been extensively studied particularly for their use as electrophotographic photoreceptor materials, optical recording materials and photoelectric conversion materials.
In general, phthalocyanine compounds are known to show several different crystal forms depending on the process of production or the process of treatment. The difference in crystal form is known to have a great influence on their photoelectric conversion characteristics. For example, known crystal forms of copper phthalocyanine compounds include .alpha.-, .epsilon.-, .pi.-, .chi.-, .rho.-, and .delta.-forms in addition to a stable .beta.-form. It is known that these crystal forms are capable of interconversion by mechanical strain, a sulfuric acid treatment, an organic solvent treatment, a heat treatment, and the like as described, e.g., in U.S. Pat. Nos. 2,770,629, 3,160,635, 3,708,292, and 3,357,989. Further, a relationship between the crystal form of copper phthalocyanine and electrophotographic sensitivity is described in JP-A-50-38543 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
With respect to titanyl phthalocyanine, too, various crystal forms have been proposed, including a stable .beta.-form as disclosed in JP-A-62-67094, an .alpha.-form as disclosed in JP-A-61-217050, and other crystal forms as disclosed in JP-A-63-366, JP-A-63-20365, JP-A-64-17066, and JP-A-1-153757.
However, any of the above-described phthalocyanine compounds proposed to date is still unsatisfactory in photosensitivity and durability when used as a photosensitive material. It has thus been demanded to develop a phthalocyanine compound of new crystal form or a process for easily preparing a phthalocyanine compound of stable crystal form.